Chi 1.0 reference manual

The Chi 1.0 Language Reference Manual describes the syntax and the static semantics of all available Chi 1.0 language constructs in a compact manner. It is set up as a reference manual, intended for users that know the language but need a more precise and complete description of a construct

Modeling and analysis of manufacturing systems

The dynamics of manufacturing systems has been a subject of study for several decades. Over the last years, manufacturing systems have become more and more complex. A good understanding of the dynamics of manufacturing systems has therefore become even more important. The goal of this report is to introduce a large variety of models that have been used for modeling manufacturing systems. By means of examples it is illustrated how certain modeling techniques can be used to derive models that can be used for analysis and/or control. Also, references are provided that can be used as a starting point for getting more details. Furthermore, recent developments in the modeling, analysis and control of manufacturing systems are presented

Multi-domain modelling, simulation, and control

For the design of large industrial systems, usually many different modelling languages are required. Currently, different projects aim at the development of standards that enable interaction between simulation models written in different languages. The Chi project aims at providing one language suited to modelling, simulation and control of systems from different application domains. Models may range from pure continuous-time models to pure discrete-event models, and any combination of the two. Due to the orthogonal design of the Chi language and careful selection of the language primitives, the core of the language is small. At the same time, the high-level data modelling constructs and high-level behaviour modelling constructs provide the modeller with expressive power. Verification of Chi models is currently limited to discrete-event models. The Chi language and simulator have proved themselves in many industrial projects involving discrete-event modelling and simulation. For continuous-time and hybrid systems, the current simulator provides time-event and state-event handling, root location, initial state calculation, handling of discrete-event sub-phases, and index 1 DAE solving. For real-time control, Chi models can be compiled to run on real-time operating systems such as VxWorks

Performance analysis for tandem manufacturing lines under variable structure production control method

In this paper we introduce novel results for the performance of the surplus-based decentralised production control method. The main objective of this production method is to guarantee that the cumulative number of produced products follows the cumulative production demand on the output of any given network. As a starting point of our research a general idea of this method is presented for the case of one manufacturing machine. Then our analysis is extended to a line of N machines. The proposed methodology is reformulated in terms of variable structure control. The production flow process is described by means of difference equations and, in order to analyse the performance, the Lyapunov theory approach is exploited. The results obtained for the production error bounds for each machine in the line and for the buffer content bounds for each intermediate buffer are discussed. Performance and robustness issues of closed-loop flow line models are illustrated by numerical simulations. It is shown that the method can be implemented in enterprise planning tools